There has been significant effort over the past several decades to increase the efficiency of combustion engines or reduce the emissions of such engines. Some of these efforts have focused on the actual system design, and particularly the fuel delivery, injection, and combustion systems and processes.
Most efforts to increase the efficiency of internal combustion engines have to date achieved only marginal success at best, resulting in only a slight increase in actual efficiency and/or using approaches that are technologically or practically not workable (e.g., involving fuels that are not readily available or safely used, or adding tremendous cost and complexity to the engine).
However, U.S. Pat. No. 7,861,696, issued Jan. 4, 2011 to the present inventor and commonly owned herewith, discloses a significant advance over prior efforts to increase efficiency. This patent describes a multi-fuel co-injection system wherein, e.g., a liquid fuel (e.g., diesel) and a gaseous fuel (e.g., hydrogen) are mixed together (e.g., under real-time microprocessor control), and applied under pressure to the injector pump of an internal combustion engine. The patent also discloses the use of a circulation loop through which the fuel mixture is circulated under pressure, and from which the fuel mixture is fed to the engine injector pump.
Likewise, International Publication No. WO2009/142769 published on Nov. 26, 2009 by the present inventor and commonly owned herewith, discloses a fuel composition for use in an internal combustion engine comprising a homogeneous mixture of liquid fuel(s) and gaseous fuel(s) made homogeneous prior to introduction to the injection system of the engine, to promote atomization of the liquid fuel(s) in the combustion chamber, thereby improving combustion and increasing efficiency.
Similarly, International Publication No. WO2011/041705 published on Apr. 7, 2011 by the present inventor and commonly owned herewith describes a homogenizing fuel enhancement system utilizing a circulation system including an infusion volume to deliver a homogeneous mixture of gaseous and liquid fuel to the injection system of the engine. In flowing through the infusion volume the gaseous fuel is infused into the liquid fuel and the mixture rendered more homogeneous. The use of various embodiments of infusion tubes to constitute the infusion volume is also disclosed.
However, such systems can create higher than conventional back pressures that stress engine components (such as, e.g., fuel injectors and flow regulating solenoid valves) and make the engine run unevenly, resulting in less-than-optimal efficiencies, and ultimately damaging the engine. There remains a need to accommodate such high back pressures, without degrading system efficiency or causing potentially damaging cavitation in pumps operating on gaseous-liquid fuel mixtures. Further, in some cases the gaseous component employed in such systems is particularly volatile, e.g., hydrogen. There remains a need to improve mechanisms for managing gaseous component outgassed from the system and avoiding potentially dangerous buildup of such gaseous component. There also remains a need for a simple and inexpensive control system for such homogenizing fuel enhancement systems.